T-DNA-encoded auxin formation in crown-gall cells

Kemper, Elke; Wafenschmidt, S.; Weiler, Elmar W.; Rausch, Thomas; Schröder, Joachim

doi:10.1007/bf00393516

Cited by 63 publications

(33 citation statements)

References 22 publications

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“…NAM is a synthetic structural homologue of IAM and the reaction product, NAA, like IAA is a strong auxin. In agreement with this observation, a similar behavior has previously been reported for the IaaH gene product of A. tumefaciens which shows enzymatic activity not only against IAM, but also against NAM and phenylacetamide to nearly the same extend (Kemper et al 1985). The AMIl-catalyzed conversión of all other tested substrates was under 15% of the IAM valué, thus, pin-pointing AMIl to be a specific IAM hydrolase with distinct enzymatic features, differing from those of FAAH.…”

Section: Discussionsupporting

confidence: 87%

Subcellular localization and tissue specific expression of amidase 1 from Arabidopsis thaliana

Pollmann

Neu

Lehmann

et al. 2006

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Amidase 1 (AMIl) from Arabidopsis thaliana converts indole-3-acetamide (IAM), into indole-3-acetic acid (IAA). AMIl is part of a small isogene family comprising seven members in A. thaliana encoding proteins which share a conserved glycine-and serinerich amidase-signature. One member of this family has been characterized as an iV-acylethanolamine-cleaving fatty acid amidohydrolase (FAAH) and two other members are part of the preprotein translocon of the outer envelope of chloroplasts (Toe complex) or mitochondria (Tom complex) and presumably lack enzymatic activity. Among the hitherto characterized proteins of this family, AMIl is the only member with indole-3-acetamide hydrolase activity, and IAM is the preferred substrate while iV-acylethanolamines and oleamide are not hydrolyzed significantly, thus suggesting a role of AMIl in auxin biosynthesis. Whereas the enzymatic function of AMIl has been determined in vitro, the subcellular localization of the enzyme remained unclear. By using different GFP-fusion construets and an A. thaliana transient expression system,

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Section: Discussionsupporting

confidence: 87%

Subcellular localization and tissue specific expression of amidase 1 from Arabidopsis thaliana

Pollmann

Neu

Lehmann

et al. 2006

Planta

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“…In the present study, IAA-amide conjugates were the major conjugate formed in the transgenic plants. It should be noted, however, that apart from hydrolyzing indole-3-acetamide to IAA, the IaaH hydrolase has also been reported to hydrolyze other compounds in an in vitro assay (Kemper et al, 1985). In that study, the IAA-ester conjugates IAIns and IAGluc were hydrolyzed to IAA by enzyme extracts from Escherichia coli expressing iaaH, whereas IAA-amide conjugates such as IAAsp and IAGlu were not.…”

Section: Discussionmentioning

confidence: 82%

Conjugation of Indole-3-Acetic Acid (IAA) in Wild-Type and IAA-Overprodcing Transgenic Tobacco Plants, and Identification of the Main Conjugates by Frit-Fast Atom Bombardment Liquid Chromatography-Mass Spectrometry

et al. 1993

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Transgenic plants overproducing indole-3-acetic acid (IAA) from expression of the Agrobacterium tumefaciens T-DNA IAA biosynthesis genes were used to study the conjugation of IAA. At the 11-node stage, free IAA, as well as ester-and amide-conjugated IAA, was analyzed in wild-type tobacco SR1 and in transgenic plants denoted 35S-iaaMliaaH (line C) and 35s-iaaM X 35s-iaaH ( l h e X). The transgenic plants contained increased levels of both free and conjugated IAA, and the main increase in IAA conjugates occurred in amide conjugates. Two amide conjugates were identified by fritfast atom bombardment liquid chromatography-mass spectrometry as indole-3-acetylaspartic acid (IAAsp) and indole-3-acetylglutamic acid (IACIu), and one ester conjugate was identified as indole-3-acetylglucose. IAAsp and IAClu were also identified as endogenous substances in wild-type plants. In wild-type plants, the percent of total IAA in the free form was significantly higher in young leaves (73 2 770, SD) than in old leaves (36 2 8%), whereas there was no difference between young (73 2 8%) and old internodes (70 f 970). In IAA-overproducing transformants, both free and conjugated IAA levels were increased, but the percent free IAA was maintained constant (57 2 10%) for both leaves and internodes, independent of the total IAA level or tissue age. These results suggest that synthesis or transport of IAA conjugates is regulated in the vegetative wild-type plant, and that different organs possess a unique balance between free and conjugated IAA. The IAA-overproducing plant, however, acquires a lower proportion of free IAA i n the stem and younger leaves, presumably determined by a higher conjugation in those tissues compared with wild type.

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“…Those infected with Pseudomonas (Kosuge et al 1966, Morris 1986, Agrobacterium (Thomashow et al 1984, Van Onckelen et al 1985, Kemper et al 1985 or Bradyrhizobium (Sekine et al 1988), however, have been found to biosynthesize IAA via indole-3-acetamide (IAM) of the product catalyzed by tryptophan monooxygenase (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Growth and development, and auxin polar transport of transgenic Arabidopsis under simulated microgravity conditions on a three-dimensional clinostat.

2003

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Growth and development, and auxin polar transport in Arabidopsis thaliana transformed with iaaH gene were studied under simulated microgravity conditions on a three-dimensional (3-D) clinostat. Simulated microgravity conditions on a 3-D clinostat did not affect the number of rosette leaves but promoted the growth and development (fresh weight of plant and the elongation of flower stalk) of transformants. Final growth of transformants under simulated microgravity conditions on a 3-D clinostat was almost equivalent to that grown on 1 g conditions in the presence of 1 µM IAM (indole-3-acetamide). The activities of auxin polar transport in the segments of flower stalk (inflorescence axis) of transformants grown on 1 g conditions were significantly promoted by the addition of IAM. Interestingly, simulated microgravity conditions on a 3-D clinostat also promoted the activities of auxin polar transport of transformants grown on the medium with or without IAM. Based on the results in this study, transgenic plants may not have an efficient homeostatic mechanism for the control of growth and development, and auxin polar transport activity in microgravity conditions in space.

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T-DNA-encoded auxin formation in crown-gall cells

Cited by 63 publications

References 22 publications

Subcellular localization and tissue specific expression of amidase 1 from Arabidopsis thaliana

Subcellular localization and tissue specific expression of amidase 1 from Arabidopsis thaliana

Conjugation of Indole-3-Acetic Acid (IAA) in Wild-Type and IAA-Overprodcing Transgenic Tobacco Plants, and Identification of the Main Conjugates by Frit-Fast Atom Bombardment Liquid Chromatography-Mass Spectrometry

Growth and development, and auxin polar transport of transgenic Arabidopsis under simulated microgravity conditions on a three-dimensional clinostat.

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